GALAXY

A. Understanding Galaxies

Galaxies are clusters of billions of stars. Usually about 100 billion

stars. Galaxies have a variety of shapes such as spirals, discs, elliptical or

irregular. Galaxy where our solar system is the Milky Way galaxy (milky

way). The numbers of galaxies in the universe are now an estimated 100

billion galaxies.

Galaxy is a system bound by gravity which consists of (in all its

manifestations, such as neutron stars and black holes), gas and cosmic dust

interstellar medium, and the possibility of a hypothetical substance known as

dark matter. The word galaxy derives from the Greek Galaxias which means

"milk," which refers to the Milky Way (English: Milky Way).

B. Galaxy Formation Process

Formation and galaxy growth is expected to occur as a result of the

force of gravity between galaxies or joint sub sub galaxies that process occurs

constantly.

C. The characteristics of Galaxies

Galaxy is set by billion, even by trillion of star

All galaxies have a nucleus of the galaxy system

The entire system is contained in the galactic rotation

The galaxy has its own light, not reflected light

The galaxies are only visible outside the Milky Way Galaxy line

The distance between one another galaxy millions of light years

Galaxies have certain forms:

For example: a spiral, elliptical shape, and irregular shapes.

D. The Classification of Galaxies

According to the morphology, the galaxy is divided into 3 types,

namely spiral galaxies, elliptical galaxies, and irregular galaxies of this

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division is based on the shape or appearance of galaxies - galaxies. Galaxies

were observed and studied by astronomers so far consists of 75% spiral

galaxies, elliptical galaxies 20%, and 5% irregular galaxies. But this does not

mean that spiral galaxies are the most numerous galaxies in the universe ini. In

fact most abundant in the universe are elliptical galaxies. If we take the same

volume of space, we will find more elliptical galaxies than spiral galaxies. It's

just that many galaxies of this type are very faint, so it is very difficult to see.

The classification are:

1. The Elliptical Galaxy

In accordance with its name, such

as elliptical appearance. But the original

form is not known with certainty because

we do not know the direction we look,

whether from front, side, or top of the

galaxy.

The Characteristics of Elliptical Galaxies

Type of galaxies range from circular to oblate spherical.

The structure of this galaxy is not seen clearly.

Looks very dim

Very few contain interstellar material.

Its members are the stars - old stars.

Kinds of Elliptical Galaxies

a. The Messier 87 Galaxy

The heart of the galaxy known as M87 is a place of unimaginable

violence. A black hole up to seven

billion times as massive as the Sun sits

at the galaxy's center -- one of the most

massive black holes ever measured. As

gas spirals into the black hole, it's

heated to millions of degrees, so it

produces enormous amounts of X-rays.

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Some of the hot gas around the black hole shoots back into the galaxy in

powerful jets that span thousands of light-years.

M87 is at the center of the Virgo Cluster.M87 contains many more

stars and is perhaps 10 times as massive as the Milky Way., it was one of

the first galaxies suspected to have a black hole, based on observations

conducted in the early 1980s.

b. The Messier 32 Galaxy

Messier 32 (also known as NGC 221 and Le Gentile) is a dwarf

elliptical galaxy about 2.65 million light-years away in the constellation

Andromeda. M32 is a satellite galaxy of

the famous Andromeda Galaxy (M31) 

M32 contains a supermassive

black hole. Its mass has been estimated to

lie between 1.5 and 5 million solar

masses.

c. The Messier 59 galaxy

Messier 59 (also known as M59 or NGC 4621) is an elliptical

galaxy in the constellation Virgo. Messier 59 and the nearby elliptical

galaxy.

Messier 59's core contains

a supermassive black hole, with a mass

that has been estimated to be 270 million

times the mass of the Sun. He has an

inner disk of stars and is very rich

in globular clusters, with a population of

them that has been estimated in around 2200.

2. The Spiral Galaxy

This type of galaxy is the most common type known to people.

Most likely due to the spiral shape that beautiful. Section - the main part is

a spiral galaxy halo, including the field of the galaxy's spiral arms and the

bulge, and the central part of the galaxy that prominent. Globular clusters 3

that are forming halo with star - a star that

is not contained in the plane of the

galaxy.

The Characteristics of Spiral Galaxy

Form a beautiful spiral.

Consists of - old stars and star - a

young star.

Star - big stars are in globular clusters scattered envelop galaxies.

This galaxy is rotating at a speed much faster than elliptical galaxies.

And because the rotational speed causes the galaxy and form a

flattened galactic plane.

The rotational speed of each part of the spiral galaxies are not the

same. Increasingly towards the galactic center speed greater.

Star - starlets are on spiral arm galaxy located in the galactic plane.

The Kinds Spiral Galaxies

a. The Andromeda Galaxy

Andromeda galaxy Messier 31 with another name, M31, or NGC

224 is one of the galaxies outside the Milky Way visible to the naked eye,

as long as seen on a clear night, with

no moon and no light pollution. The

structure is similar to the Milky Way

is a spiral-shaped. The distance is

about 2.5 million light years. It's in the

sky is in the northern hemisphere sky,

about 41 degrees to the north of the celestial equator, both observed

around the month of September, October and , November.

Andromeda size can be more than 7 times the angular diameter of

the moon. This galaxy contains about one trillion stars, and moving toward

the Milky Way at a speed of about 300 km / sec.

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b. The Milky Way galaxy

Milky Way galaxy of 400 billion stars, with a diameter of about

130,000 light-years away (one light year is 9.500 billion kilometers). The

Milky Way is home to our sun and its planets surrounding it. This spiral

galaxy with an average size, and always forms a new star every year.

c. The Sombrero Galaxy

The Sombrero Galaxy (also known as M104 or NGC 4594) is an

unbarred spiral galaxy in the constellation Virgo. Has a bright nucleus, an

unusually large central bulge, and a prominent dust in a disk inclined road.

Dark dust lane and the bulge give

this galaxy the appearance of a

sombrero. The galaxy has an

apparent magnitude of +9.0, making

it easily visible with amateur

telescopes.

d. The Black Eye Galaxy

A spiral galaxy in the

constellation Coma Berenices,

Messier 64, the famous "Black

Eye" galaxy or the "Sleeping

Beauty galaxy," has a

spectacular dark band of dust in

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front of the absorbing intelligent galactic nuclei appear small

when observed with Telescope.

e. The 2MASX J00482185-2507365 occulting pair galaxy

2MASX J00482185-2507365 occulting

pair is a pair of overlapping spiral galaxies

found around NGC 253, the Sculptor Galaxy.

This pair of galaxies illuminates the distribution

of galactic dust beyond the visible spiral arms

of galaxies.

f. The Whirlpool Galaxy

The Whirlpool Galaxy is also known as Messier 51A, M51A, or

NGC 5194, the Whirlpool Galaxy is an interacting

grand-design spiral galaxy located at a distance of

about 23 million light-years away in the constellation

Canes Venatici. This is one of the most famous spiral

galaxies in the sky. Galaxies are easily observed, can

be seen with binoculars.

g. The Messier 81 Galaxy

Located in the northern constellation Ursa Major, is one of the

brightest galaxies visible in the skies of

planet Earth. This incredible detailed view

reveals a bright nucleus, a large spiral arms

and sweeping cosmic dust lane with a scale

comparable to the Milky Way.

h. The NGC 1512 Galaxy

Including the constellation

Horologium, Galaxy NGC 1512 is quite

similar to the great Milky Way. Is a

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starburst galaxy core ring, which is a remarkable circle of young star

groups that include several light years.Galaxy "starbursts" are episodes of

vigorous formation of new stars and galaxies are found in a variety of

environments.

i. The Grand Spiral Galaxy

Grand Spiral Galaxy also known as

NGC 123, this fascinating galaxy is

dominated by millions of bright stars and

dark dust, caught in a vortex gravity spiral

arms rotate around the center of the galaxy

3. The Irregular galaxy

Irregular galaxy is a galaxy type is not symmetric and does not

have a specific shape. Members of this

galaxy consists of old stars and young

stars. This irregular galaxy contains a lot

of interstellar material consisting of gas

and dust.

The Characteristics of Irregular Galaxy:

This galaxy contains a lot of material

consisting of gas interstellar gas and

dust.

Consisting of - stars old and young.

The shape is not symmetric and does not have a specific shape.

The kinds of Irregular Galaxies:

a. The Large Magellan Cloud Galaxy

Large Magellan Cloud is a nearby galaxy as well as a third one

loyal companion Milky Way galaxy in which we live. The Large

Magellan Cloud galaxy is 157,000 light-years away from our Earth.

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Mass of the Large Magellan

Cloud is only about 1% of the mass

of the Milky Way or the equivalent

of 10 billion solar masses. Large

Magellan Cloud galaxy very rich in

gas and dust, with star formation

region active in it. A number of

exotic star was found inside. For

example, Supernova 1987A.

Apparent magnitude +1 so easily seen by the human eye without

any tools.

b. The Small Magellanic Cloud  Galaxy

The Small Magellan Cloud (SMC) is a galaxy. It is classified as

either a dwarf irregular galaxy or as a Magellan type dwarf spiral

galaxy. It has a diameter of about 7,000 light-years and contains

several hundred million stars.It has a total mass of approximately 7

billion times the mass of the Sun.

With a mean declination of approximately −73 degrees, it can

only be viewed from the Southern Hemisphere and the lower latitudes

of the Northern Hemisphere. It is located in

the constellation of Tucana and appears as a hazy, light patch in the

night sky about 3 degrees across. It looks like a detached piece of the

Milky Way. Since it has a very low surface brightness, it is best

viewed from a dark site away from city lights.

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